Atopic dermatitis is a chronic, relapsing, eczematoid condition that frequently occurs in patients with asthma and/or allergic rhinitis. It affects 0.5% to 1% of the general population worldwide. The cumulative incidence has been estimated to be 12% for 5 year olds and 9% to 12% for 7 year olds. The purpose of this study is to 1) test the efficacy of high dose topical sodium cromolyn in the treatment of moderate and severe atopic dermatitis by a double-blind, placebo controlled, crossover study; 2) to determine if serum levels of sICAM-1, sVCAM-1, sE-Selectin correlate with the clinical severity of atopic dermatitis; 3) to determine if high dose topical sodium cromolyn down regulates markers of allergic inflammation in patients who have moderate to severe atopic dermatitis.